Cosmic-ray detector blasts off on Space Shuttle

An instrument for detecting cosmic rays – and possibly even dark matter – has finally been lifted into orbit on board the Space Shuttle Endeavour. The Alpha Magnetic Spectrometer (AMS), which is the brainchild of the Nobel-prize-winning physicist Samuel Ting, will soon be installed on the International Space Station (ISS). Ting first came up with the idea for the AMS in the 1990s but a series of setbacks, including the Columbia shuttle disaster in 2003, has led to the mission being continually delayed.

The launch of the AMS also marks the end of an era in space exploration, as this is the final mission of NASA's Space Shuttle programme – which began with the launch of Columbia in April 1981. The lift-off from Kennedy Space Center in Florida involved celebrations commemorating the 30-year Space Shuttle programme.

Costing $2bn and weighing seven tonnes, the AMS detector uses a 0.15 T cylindrical magnet 1 m in diameter and 1 m in height to sort incoming particles according to their momentum and charge. The direction of bend of the particle tracks through the magnet's bore depends on whether the particles are matter or antimatter, while the gradient of the bend is determined by their speed. This will allow the detector to distinguish between vast numbers of different types of cosmic-ray particle.

Searching for dark matter

Physicists are particularly interested in high-energy positrons (anti-electrons), which could be produced by collisions of dark-matter particles in the Milky Way. However, the ability of the experiment to detect dark matter is controversial. The magnet inside the detector was supposed to be an 0.87 T superconducting device, which the project's scientists had spent nearly a decade designing and building. But in 2010 the researchers suddenly decided to revert to the weaker permanent magnet that had been flown on a test flight aboard the Space Shuttle in 1998.

The change was made in response to the decision to extend the lifetime of the ISS to 2020 and perhaps beyond. The superconducting magnet would only have had a three-year supply of liquid-helium coolant, leaving the AMS inoperative for most of the ISS's lifetime. In addition, tests of the AMS at CERN in early 2010 revealed that the detector heated up more than expected – which would have reduced the time that the helium held out.

Some critics claim that the new configuration will make the experiment less likely to make discoveries such as the detection of dark matter, while others insist that the changes made at such a late stage could make failure more likely.

Seeking strangelets

The AMS could also detect strangelets, which are ultra-dense clumps comprising large numbers of up, down and strange quarks. This new form of matter was first proposed in 1984 by Edward Witten, but has yet to be seen by a succession of experiments. Strangelets could be produced when high-energy cosmic rays strike Earth's atmosphere. The particles are expected to have a very high mass-to-charge ratio, which means that they should take a nearly straight path through the AMS.

AMS uses a series of silicon sheets positioned one on top of the other across the magnet's bore to sense the position of particles as they travel through the magnet. To optimize for the replacement magnet as much as possible, the AMS team has shifted two of these planes so that they now lie well outside the magnet's bore. The AMS researchers claim that the momentum resolution of the new configuration will be within 10% of that possible with the superconducting device.

The team also says that the extended running time of the experiment will allow it to gather about six times more data and boosts its chances of seeing rare cosmic-ray events. In addition, the mission could extend over an entire solar cycle, allowing it to study the effect of the Sun on cosmic-ray fluxes.

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Small factual error...

Nice article about AMS, but 2nd paragraph is wrong about this being the last shuttle launch: "...as this is the final mission of NASA's space shuttle programme...". This was the last mission for the Endeavor, but Atlantis has the distinction of being the last shuttle to launch. Mission STS-135 is scheduled for July. That will end the Shuttle era...

STS-135

Thanks for your comment. My understanding is that STS-135 has yet to gain final funding approval from Washington for launch. However, NASA seems adamant that the mission will go ahead approval or not. Hamish

Nice article about AMS, but 2nd paragraph is wrong about this being the last shuttle launch: "...as this is the final mission of NASA's space shuttle programme...". This was the last mission for the Endeavor, but Atlantis has the distinction of being the last shuttle to launch. Mission STS-135 is scheduled for July. That will end the Shuttle era...

Mass:charge ratio

If strangelets have high mass:charge ratio, how neutrinos rate? Would a low ratio help explain why they don’t interact much? [Here I'm assuming neutrinos are neutral to everything but a level of charge we haven't yet specified, Majorana perhaps.]

My quick summary sent to Prof.Ting & NASA

Read news on “NASA Installs Device at Space Station in Long-Sought Quest for Antimatter”- a $2 billion cosmic ray detector, and delighted scientists immediately began detecting “thousands and thousands” of subatomic particles from deep space.

I hate to disappoint Prof. Ting, the scientists and NASA- but, there is no antimatter in the Universe (unless it is a misname for dark-matter). We can’t observe or sense dark-matter directly… period. I think, the $2 billion experiment will end up like CERN’s $10 billion experiment, and $750 million gravity probe-B experiment or the rest of the experiments- for Big bang, BH etc.. etc.. You can discover the Reality indirectly from the clue given by Kepler-Newton…, and the rest of work is misplaced, including Bohr atom model, atom-nucleus, electron shell-structure, particle std. model etc.. etc... NASA and the scientists will have no other choice, but accept Indra (Neutron) as the center of our-universe, not the Sun (per Galileo…); and, accept that we live in an Atom (Anuvu)- and, all experiments centered on Sun are bound to fail…, like those who thought Earth is the center of universe before Galileo… Please feel free to write when you are ready to see the Reality..

Covers new ground

This detector will open a window on anti-matter in our cosmos since anti-matter rarely makes it through the atmosphere for earth mounted experiments. Decades long measurements of the prevalence and variety of matter and anti-matter will answer many questions. The anti-hydrogen experiments at CERN will complement this detector by answering the question; "does anti-matter fall up?", which could make anti-matter very rare in the high gravity in our solar system.

This detector will open a window on anti-matter in our cosmos since anti-matter rarely makes it through the atmosphere for earth mounted experiments. Decades long measurements of the prevalence and variety of matter and anti-matter will answer many questions. The anti-hydrogen experiments at CERN will complement this detector by answering the question; "does anti-matter fall up?", which could make anti-matter very rare in the high gravity in our solar system.

What is anti-hydrogen? Can you explain? First of all our-scientists have no clue what is hydrogen, except to say 'H' is a proton+ a electron...; but, they have no clue proton, electron can't survive (much time) without 'neutron': the creator-destroyer. Getting back to anti-hydrogen (-H): does that mean the elctron in -H orbits in reverse direction to that of H? How did CERN create -H? And, what is its life span?